This invention relates to the determination of unwanted deposit formations in an opaque fluid stream employed for industrial or manufacturing processes. Determination is made in situ or by real time analysis, or near to it, rather than by extracting a sample of the fluid for external laboratory analysis elsewhere.
There are numerous examples of industrial fluid streams confined by a conduit for manufacturing purposes where entrained biological growths or organic impurities deposit on and reduce the efficiency of equipment employed in processing the fluid. Not only that, the finished product may be contaminated by the film.
A good example is paper making machinery when the confining conduit is the paper machine itself. Bacteria colonies, protozoa and other simple life forms become entrained in the pulp. These feed and thrive on indigenous substances such as proteins, oils, carbohydrates and polysacharides. The colony expands and becomes a gummy, sticky biofilm which can trap other particles and deposit on the walls of the chest and other equipment in the pulp confining conduit downstream of the chest. The equipment becomes fouled. Not only that, the unwanted films are loosened due to turbulence and become part of the paper, resulting in grade degradation. Pitch (hydrophobic contaminants) present as part of the wood fibers is another source of an unwanted organic deposits.
The same phenomena are involved in cutting oils as another example. The purity and efficiency of the oil are degraded, the surfactant which maintains the cutting oil as an emulsion is adversely affected, and film deposits on the workpiece being machined.
In our co-pending application Ser. No. 07,754,016, filed Sep. 3, 1991 we address the problem of film formers in a transparent process stream such as cooling tower water, undertaking a double beam transmittance comparison (reference and sample) to detect film build-up. In the present invention, we address the same problem (film growth or build-up) in an opaque stream where light transmittance is difficult if not impossible to measure accurately. Instead, we use light reflectance as will be explained.